The present invention relates generally to an apparatus and method for treatment of stenotic or diseased lumens. More particularly, the invention relates to a novel balloon catheter and method of treatment of a chronic total occlusion of a lumen.
Balloon angioplasty, atherectomy, and stent implantation are common procedures for the treatment of stenotic or diseased lumens. Such procedures are performed percutaneously, through an incision site remote from the site of treatment within the lumen. These procedures consequently require tracking of the treatment device from the incision site, through the vasculature and to the lesion. The vasculature is typically tortuous and may have numerous stenoses of varying degrees throughout its length. In order to place the distal end of a catheter at the treatment site, a guidewire is first tracked from the incision, through the stenosis, and across the lesion. Then, a catheter bearing a balloon and/or other device such as, for example, a stent, at its distal end can be tracked over the guidewire to the treatment site. Ordinarily, the distal end of the guidewire is quite flexible in order that, as it is pushed through the lumen, it can xe2x80x9cfindxe2x80x9d its way through the turns of the typically irregular passageway of the lumen without damaging the lumen.
In some instances, the extent of occlusion of the lumen is so severe that the lumen is nearly completely obstructed, leaving virtually no passageway for the guidewire. Such a condition may be described as a xe2x80x9ctotal occlusionxe2x80x9d. Where such a condition persists longer than six months, the lesion is referred to a xe2x80x9cchronic total occlusionxe2x80x9d. Further, in the case of diseased blood vessels, the lining of the vessels may be characterized by the prevalence of atheromatous plaques, which may form a total occlusion. The extensive plaque formation of a chronic total occlusion typically has a fibrous cap surrounding softer plaque material. Such a fibrous cap may present a surface which may be difficult to penetrate with a conventional guidewire. In such instances, the typically flexible distal tip of the guidewire may be unable to cross the lesion, and in order to successfully cross and treat a chronic total occlusion, alternative devices may be required. For example, at a minimum, a stiffer guidewire may be required to traverse the stenosis. Or, an atherectomy device may be required to penetrate the occlusion. Hereinafter, Applicants refer to any device intended to penetrate the occlusion, including a guidewire, as a recanalizing device.
In the event that a recanalizing device and/or greater force by the clinician are required in order to create a passageway through a chronic total occlusion, additional precautions must be taken to prevent injury to the vessel wall. For example, it is imperative that the guidewire and/or atherectomy device be centered within the vessel to avoid penetration of the vessel wall. Further, visualization of the location of the guidewire or atherectomy device exit port is desirable. Therefore, the device and method for centering the recanalizing device within the vessel must confer a high degree of confidence on the clinician, both in centering and in visualization, in order that a passageway can be safely created.
Additionally, in the instance where a stiffer guidewire or other device is required in order to cross the lesion, the guidewire will meet increased resistance upon attempts to penetrate the plaque. Consequently, the guidewire or other device will require increased support proximal of the lesion. That is, when the tip of the guidewire abuts the plaque, and as pressure is exerted upon the guidewire in order to penetrate the lesion, portions of the guidewire proximal of the tip will require the support of a catheter encasing the guidewire. Such xe2x80x9cback supportxe2x80x9d will prevent excessive prolapse of the guidewire or other device within the vessel proximal of the stenosis and will ensure that the recanalizing device remains centered within the lumen.
Further, when the tip of the guidewire or recanalizing device meets increased resistance to penetration of the lesion, an additional result may be a tendency of the catheter to slide proximally over the guidewire. Such proximal sliding will result both in a failure to maintain the recanalizing device centered within the vessel and in a failure to provide back support to the device. Such a tendency may be recurring with repeated attempts to traverse the stenosis, rendering the process increasingly frustrating for the clinician. Means for securing the catheter within the vessel may be required during attempts to penetrate an extensive lesion.
Angioplasty catheters and stent delivery catheters of the prior art lack means for adequate visualization, centering, support and securement of the catheter for treatment of extensive lesions. Similarly, devices bearing cutting heads or other devices for creating a guide wire passage lack means for sufficiently centering the device prior to penetrating the occlusion. Therefore, the prior art devices lack sufficient safeguards and back support for using a stiffer guidewire and lack the essential safeguards for centering a cutting device intended to penetrate an extensive occlusion.
The present invention provides an apparatus for improved centering of a device which is intended to penetrate a severe occlusion of a body lumen. Further, a device according to the present invention allows for better fluoroscopic visualization, and therefore placement, of the device with respect to the lesion. A device according to the present invention also provides back support for a recanalizing device during attempts to penetrate an extensive occlusion. Still further, a device according to the present invention provides a friction fit of the device with the vessel wall during attempts to cross a lesion, preventing proximal sliding of the device during attempts to cross the lesion. According to the present invention, a catheter with a substantially central lumen for receiving a guidewire and/or other recanalizing device is provided. Further, the central lumen of a catheter according to the invention comprises an exit port which is not distal to the inflatable member of the catheter. An alternative embodiment of the invention also comprises a central lumen for receiving a second catheter for the purpose of conducting an angioplasty procedure and/or delivering a stent. Further, a method of making an inflatable member for use in an apparatus according to the invention is provided.